Today, we link land to land. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.

Henry Petroski has written
much about bridges. Now he looks at a bridge just
being completed -- the Confederation Bridge linking
Prince Edward Island to mainland New Brunswick.
This bridge, including a mile of approach spans, is
eight miles long and it's costing just under a
billion dollars. As the bridge nears completion,
over 40 piers, 800 feet apart, march across the
water, rising 130 to 200 feet from the sea bottom.
This is one of the last really heroic constructions
of the twentieth century.

But Petroski isn't here to tell us about the
wonders of his own field of civil engineering.
Rather, he's writing about what he calls the fixed
link question -- an ongoing engineering dilemma.

Tunnels and bridges form fixed links between two
land masses. When I visited Prince Edward Island in
the late '70s, a ferry boat took me to a completely
quiet and rural farming community. It was Canada's
smallest province, about the size of Delaware and
home to only 100,000 people. It was peaceful and
bucolic.

By contrast, consider Manhattan Island, tied by
vast bridges and tunnels to New Jersey, Long
Island, and the Bronx. The only place New Yorkers
still routinely visit by ferry is Staten Island.

There's nothing bucolic about Manhattan Island. Its
fixed links to the surrounding world have converted
it to the high-pressure center of America --
off-center though it may be.

England lies on another island only recently
connected to mainland Europe by a fixed link, the
Channel Tunnel. Technology that could have built a
Chunnel has existed for over a century. But this
link has stirred fear as long as engineers have
dreamt it. The English feared it would let in rabid
animals, or the French, or anything else that goes
bump in the night. But before you laugh, wait a few
years. England will be changed, and we don't yet
know just how.

While no one can know just what this bridge across
Northumberland Strait from New Brunswick to Prince
Edward Island will do, it has awakened plenty of
resistance. It will certainly hurt the ferry
business. You can bet it will end the pastoral
isolation of the Island. Then there's environmental
impact: bridge piers tend to anchor ice that
would've broken up much sooner. That can delay
fishing and hurt the Island's economy. But the
bridge will also bring in tourists. And, through
better commerce, it'll be a force that cuts the
Island's high unemployment rate by putting it in
balance with the rest of Canada.

Now those spans march across the water carrying
radical change to a quiet land. The genie of
technology won't stay in its bottle. That genie
always turns the known world upside down, and
Petroski's fixed links are among the most powerful
agents of technological change we know. The march
of the Confederation Bridge is as inexorable as
entropy -- and as sure as tomorrow's dawn.

I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.